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Posted at 01:16 PM ET, 10/25/2011

Hurricane Rina strengthens, on track towards Yucatan


Hurricane Rina as seen from NOAA GOES 13 at 12:30 EDT. (NASA)

Hurricane Rina has intensified over the past day, reaching category 2 strength. Aircraft reconnaissance penetrations have recently observed maximum sustained winds near 105 mph (90 knots; pressure 971 mb), just 6 mph shy of category 3 intensity. Positioned about 300 miles southeast of Cancun, Mexico, it’s on a slow west-northwest jog at about 3 mph.

Conditions are expected to begin deterioriating over the eastern Yucatan in the next 24-36 hours with a possible landfall on Thursday. Hurricane warnings are posted along much of Yucatan Peninsula’s east coast in Mexico, including Cancun.

Despite its continued strengthening, Rina did not deepen explosively overnight, especially when compared to some big storms in recent times that moved across a similar sector of the tropics.

For example, Hurricane Wilma’s pressure dropped 100 mb in 27 hours (while the wind went from 70 mph to over 170 mph) as it moved over the same part of the Caribbean back in late October 2005. Fortunately, we are not dealing with a situation as dire.

Satellite appearance and near-term intensity

Rina’s tempered rate of intensification may reflect the vast extent of the surrounding exceptionally dry air (shaded in orange in the image below) as discussed yesterday.

The satellite presentation of the storm itself looks healthy for now, with thunderstorm clouds widely distributed across the vortex, and the cirrus-cloud outflow nearly unrestricted in the northeast quadrant.

In the image below, you can actually see a trail of clouds extending from Rina northeastward towards the middle part of the Atlantic. In some circumstances, a cloud pattern like this would actually favor the quick intensification of a tropical cyclone, owing to the apparent existence of an unobstructed outflow channel. But in this case, the dry air to the north may be too much to overcome.


Water vapor image of Rina, showing dry air to the north (NOAA)

It’s hard to imagine that, with such dry air in close proximity to Rina’s core, that it will not put at least some kind of brake on further development. In fact, it may even be doing that now, as close-up satellite images show a not-so symmetric, somewhat ragged appearance.


Close-up water vapor image of Rina from Tuesday morning (NOAA)

Nevertheless, some modest stregthening is possible and the National Hurricane Center predicts it will become a major category 3 hurricane in the next day.

Impacts over the Yucatan

As long as Rina remains in this part of Caribbean atmosphere, it will remain a significant concern to nearby land masses.

Fortunately, the radius of hurricane force winds is only 15 miles (for now). With the center of this extremely compact storm expected to approach the Yucatan coast Thursday morning at hurricane strength, destructive wind gusts would surely accompany an eyewall passage, but probably not extend outward much beyond that, especially if the center of Rina parallels the coast on a northward track. Rainfall amounts in a much larger swath could reach 8 to as much as 16 inches due to the storm’s slow forward motion. Flooding may well be Rina’s most significant impact.

Long-term track: Florida in play?

A substantial northward movement into the Gulf of Mexico appears unlikely. Most models agree that Rina will not make it north of 25N.


Rina track forecasts ( National Center for Atmospheric Research )
Many of them still turn the cyclone around and move it back to the south beyond the 5-day forecast period shown above. The probability of a Florida hit is still low, but not out of the question, with some recent model runs suggesting a more northeastward course. We will watch that closely for you in the coming days.

In the unlikely event Rina were to get pulled northward toward the United States, the odds are that it would be coupled with a midlatitude weather system strong enough to seriously damage its tropical characteristics and irreversibly weaken the circulation.

By  |  01:16 PM ET, 10/25/2011

Categories:  Latest, Tropical Weather

 
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